All female spiders are great mothers. Eggs are laid in silken sacs that, in most cases, are tucked away in a safe place under leaves or debris or closely guarded by the female. For free-ranging Wolf Spiders, they take their egg sacs with them – securely attached to the spinnerets located at the end of their abdomens.
Seeing a spider with a white ball attached to its backside is a head-turning event even for those of us that look for spiders. For Wolf Spiders, they take parenting to the next level by carrying their newly hatched young on their backs – the spider equivalent of opossums.
For these free-roaming spiders, this makes sense. Unlike web-building spiders, they do not stay in one place. Being a protective parent means taking the children along for the ride. But there is a lot to do to pack up the eggs for the journey.
As with most spiders, the process begins by laying down what will become the bottom half of a shallow silken bowl. Fertilized eggs are deposited into the bowl, then covered with the top half. If you look closely at any Wolf Spider egg sac, you can see the seam where they were joined. A bit more silk to secure it to the female is all it takes to get on the road.
Should the female be disturbed or if the sac is pulled off, the mother will grab the egg sac with her pedipalps (shorter leg-like appendages next to her fangs). Only when the coast is clear, will she reattach the sac.
Once the spiderlings hatch, they actively climb onto the abdomen of their mother for a bit more time with mom. In reality, this behavior has two benefits. First, these vulnerable young do have the protection of their mother for a few more days. Mortality is high for these young, many falling victim to other spiders. Secondly, these rides on mama’s back also helps distribute young across the landscape.
So there you have it. One more cool thing to look for as you roam around your yard.
Hope to see you in our great outdoors!
Photos courtesy of Janet Wright (egg sac) and Andy O’Bryan (young spiderlings)